1. Field of the Invention
The invention relates to handover decisions for mobile terminals receiving Internet protocol (IP) streams broadcasted over digital broadband transmission networks. More particularly, the invention relates to making handover decisions based on the priority of IP streams.
2. Description of Related Art
Digital broadband transmission networks are used to transport digital data that includes High Definition TV, multiple channel standard definition TV (PAL/NTSC or SECAM) and, of course, broadband multimedia data and interactive services. An example of such a network is that defined by the Advanced Television Systems Committee (ATSC). Another example of such a network enjoying popularity in Europe and elsewhere world-wide is Digital Video Broadcasting (DVB) which, like ATSC, in addition to the delivery of television content, is also capable of delivering IP data. Both ATSC and DVB utilize a containerization technique in which content for transmission is multiplexed into MPEG-2 transport streams that act as data containers. These MPEG-2 transport streams are broadcast over plural signals and may include several IP streams.
Typical handover techniques for mobile terminals moving within or between cells involve determining which cell, carrying the currently received or requested service, has the highest signal strength. Usually it is assumed that a mobile terminal is receiving only one service at the time of handover. These techniques work well e.g. in the case where only ‘regular’ DVB services are being received. These ‘regular’ DVB services are composed of audio, video and private data streams, all needed for one service (e.g. TV program or movie). However, when digital broadband transmission networks are used to carry IP services transmitted over plural IP streams, the handover decision is not that simple. IP services are by nature different from the regular DVB services. Thus, when usually only one of those ‘regular DVB services’ is being received at the time of handover, the number of simultaneously received IP services may be easily close to 10 services or more. In the case where all available cells are providing mutually identical IP services, the problem doesn't exist and the handover decision can be based solely on the signal strength. However, this is not the case, especially when the handover is done in the network where the content of the cells is mutually heterogeneous, or moreover, when handover is done between the cells originating from two different networks.
Therefore, there is a need in the art for systems and methods to optimize handover from one cell to another cell to correspond to the needs of the user consuming services.